Prior swing aids for golfers or the like have included a variety of different devices. For example:
(a) One device can be set upon a surface and is designed to trap a golf ball inside itself in an area approximating the opening of a regulation golf cup.
(b) Other devices can be set upon a surface and have openings at least the size of the diameter of a golf cup. A golf ball that has rolled directly into one of these devices' openings rolls back into a golf ball-sized cavity at the rear of the device and moves the piston of an electro-mechanical solenoid far enough back that an electrical contact is made which energizes the solenoid's coil, propelling the piston forward. At the same time the golf ball resting on the piston is propelled backwards out of the machine; another similar device has an upwardly-inclined ramp, usually ten to fifteen feet in length, that has a recessed golf cup near its elevated end. A golf ball is set at the bottom of a green-carpeted ramp and is propelled up the ramp and into the recessed cup; if it does go into the cup an internal shoot guides the golf ball back to the hitting area. If the golf ball travels too far, it settles onto another ramp that carries the ball to the internal chute. If the ball does not go up the ramp far enough, it falls back down the ramp towards the bottom.
(c) Still further devices have a mat-like surface with a series of rows of optical and/or magnetic sensors embedded therein that are designed to catch the reflection of light off a piece of reflective tape and/or to interact with magnetic tape attached to the bottom surface of a moving golf club. The devices typically provide information that relates to (a) the speed of the moving club, (b) the distance the ball would travel if a club was swung at that speed and (c) the direction the club was moving, either an inside-out path, a straight path, or an outside-in path.
Each of these devices has certain limitations. The device that attempts to trap the ball inside itself, such as (a) above, will not trap a golf ball that is rolling straight on-line if it is travelling fast when it arrives. Also, once the golf ball has stopped, someone has to walk to the ball and retrieve it if the ball is to be replayed. For devices such as those described in paragraphs (a) and (b) above, an errant shot to the left or right of the device creates no indication as to how far away from the intended target it ended up. Most of the devices that are included in paragraphs (a) and (b) above must rely on the surface at hand, be it a deep, textured, bumpy carpeting or a floor covered with linoleum to simulate the smoothness and pace of a real grass golf green.
Devices that are described in paragraph (b) above do not return errant shots, and a golf ball on-line can jump over the back of the device if it has a little extra velocity. Also, the solenoids misfire or do not catch the golf ball squarely all the time, causing the golf ball to return improperly.
The length of a putt that can be practiced by devices described in (a) and (b) above is limited by the length of clear, unimpeded surface available and the length the user wants to travel to retrieve the golf balls. Also, the area being used is restricted from being utilized in other ways.
The devices described in paragraph (c) above are not portable or easy to move; they restrict the use of the area they're in permanently, and they cannot be conveniently used in two separate locations, such as home and office. A golf ball hit too hard can jump over the back ramp, or it can become stuck in the internal shoot, halting the ball return system until a manual extraction is performed. The length of the putt to be practiced is limited by the ten to fifteen foot length of the device. The devices that are described in paragraphs (a), (b) and (c) all have the same drawback in that different putt speeds cannot be simulated unless a drastic change in the surface used is made.
Devices such as those described in paragraph (d) above do not ascertain information about the golf shot directly from sensing the movement of the golf ball but take the indirect approach of detecting club head movement. A golf shot that is mis-hit cannot be diagnosed by examining club head movement on a horizontal plane only. A golf ball can be hit after the club head has recocheted off the surface behind the golf ball, imparting an upward blow, or a golf ball can be hit with a downward descending blow. The two swings register the same information when only being detected from a horizontal plane, while the actual results of the ball flight would be tremendously different. Also, the golf club being used must be altered by placing a piece of reflective or magnetic tape on the bottom of it. If the placing of the tape is forgotten, valuable time can be wasted until this fact is realized. In many instances a lightweight plastic ball has to be used because the movement of a regulation golf ball may cause considerable damage to life and property. The degree to which off-line club path movement can be detected is severely limited by the spacing and number of sensors used. The golf ball that is hit does not automatically return to the place from which it was hit. The putt swing, which is certainly not a full swing, is not readily detectable, and the small incremental measurements necessary for accurate putt analysis are not inherent in these devices.
Finally, all of the devices mentioned above have the drawback that any information has to be discerned by lifting of the head and the use of considerable eye movement. All the teachings on golf agree on the necessity to limit head movement, and especially upward head movement, to an absolute minimum.